Why has a healed bruise come back?

Got some blood work done 3 weeks ago and the arm that they drew it developed a bruise on the midway section of my forearm. It healed in about 6 days and my CBC showed all blood counts in the normal range. Yesterday the bruise came back ( ive been using a heavy power tool with that arm for the past 2 days that use .22 calibre shots for concrete) but havent had any other trauma happened to this arm. Not bruising anywhere else on body but the skin on my hands has been breaking fairly easily the past couple days too but im thinking this might be due to dry skin, confused about the recurrent bruise though